I would try opening the eqhost file, making the changes, then saving it to your desktop.
Then cut/paste it into your EQ directory, overwriting the old one.
If that does work try turning off UAC (this will make your system less secure but will likely get rid of half the junk you don't like about Vista)
http://www.howtogeek.com/howto/windo...windows-vista/
Vista seems to be more protective of the program files directory then previous versions of Windows.